Regulation of cyclin d

Abstract

The present invention provides methods for modulating the level or activity of cyclin D by inhibiting EGLN2 expression or activity. The methods are particularly useful for treating or preventing a disorder associated with elevated cyclin D levels or activity, such as cancer.

1 . A method for decreasing the level of cyclin D1 in a subject in need thereof, the method comprising administering to the subject an effective amount of an agent that inhibits the activity or expression of a prolyl hydroxylase, thereby decreasing the level of cyclin D1 in the subject. 
     
     
         2 . The method of  claim 1 , wherein the prolyl hydroxylase is EGLN2. 
     
     
         3 . A method for treating a disorder associated with elevated cyclin D1 levels or expression in a subject, the method comprising administering to the subject an effective amount of an agent that inhibits the activity or expression of a prolyl hydroxylase. 
     
     
         4 . The method of  claim 3 , wherein the prolyl hydroxylase is EGLN2. 
     
     
         5 . The method of  claim 3 , wherein the disorder is a cancer. 
     
     
         6 . The method of  claim 5 , wherein the cancer is selected from the group consisting of an estrogen-receptor positive cancer, an estrogen-dependent cancer, and a cancer resistant to endocrine therapy. 
     
     
         7 . The method of  claim 1  or  claim 3 , wherein the agent is a siRNA or a shRNA comprising the nucleotide sequence of SEQ ID NO. 1 or SEQ ID NO:2. 
     
     
         8 . A method for identifying a modulator of cyclin D1 levels, the method comprising:
 (a) measuring the activity of a prolyl hydroxylase in the presence and in the absence of a candidate modulator under conditions suitable for the prolyl hydroxylase to hydroxylate a polypeptide substrate in the absence of the candidate modulator;   (b) comparing the activity of a prolyl hydroxylase measured in the presence and in the absence of a candidate modulator in step (a); and   (c) identifying the candidate modulator as a modulator of cyclin D1 levels if the activity of the prolyl hydroxylase differs in the presence and in the absence of the candidate modulator.   
     
     
         9 . The method of  claim 8 , wherein the prolyl hydroxylase is EGLN2. 
     
     
         10 . The method of  claim 8 , wherein the activity of the prolyl hydroxylase is determined by measuring prolyl hydroxylation of the polypeptide substrate. 
     
     
         11 . The method of  claim 10 , wherein the polypeptide substrate is the alpha subunit of hypoxia-inducible factor or a fragment thereof containing a proline residue. 
     
     
         12 . The method of  claim 10 , wherein measuring the hydroxylation of the polypeptide substrate comprises measuring the binding of a VHL polypeptide to the polypeptide substrate. 
     
     
         13 . A method for identifying a modulator of cyclin D1 levels, the method comprising:
 (a) measuring the activity of a prolyl hydroxylase in the presence and in the absence of a candidate modulator under conditions suitable for the prolyl hydroxylase to hydroxylate a polypeptide substrate in the absence of the candidate modulator;   (b) comparing the activity of a prolyl hydroxylase measured in the presence and in the absence of a candidate modulator in step (a);   (c) identifying the candidate modulator as one that alters the activity of the prolyl hydroxylase if the activity of the prolyl hydroxylase differs in the presence and in the absence of the candidate modulator;   (d) measuring the levels of cyclin D1 in the presence and in the absence of the candidate modulator identified in step (c);   (e) comparing the levels of cyclin D1 measured in the presence and in the absence of the candidate modulator in step (d); and   (f) identifying the candidate modulator as a modulator of cyclin D1 levels if the level of cyclin D1 differs in the presence and in the absence of the candidate modulator.   
     
     
         14 . The method of  claim 13 , wherein the prolyl hydroxylase is EGLN2. 
     
     
         15 . The method of  claim 13 , wherein the activity of the prolyl hydroxylase is determined by measuring prolyl hydroxylation of the polypeptide substrate. 
     
     
         16 . The method of  claim 15 , wherein the polypeptide substrate is the alpha subunit of hypoxia-inducible factor or a fragment thereof containing a proline residue. 
     
     
         17 . The method of  claim 15 , wherein measuring the hydroxylation of the polypeptide substrate comprises measuring the binding of a VHL polypeptide to the polypeptide substrate. 
     
     
         18 . A method for identifying a modulator of EGLN2 expression or activity, the method comprising:
 (a) measuring the levels of cyclin D1 in the presence and in the absence of a candidate modulator;   (b) comparing the levels of cyclin D1 measured in the presence and in the absence of a candidate modulator in step (a); and   (c) identifying the candidate modulator as a modulator of EGLN2 expression or activity if the levels of cyclin D1 differs in the presence and in the absence of the candidate modulator.